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Activities, Education and Training, Featured, General, Station Equipment

My Portable Gear and Organizing for a POTA Event

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One of the problems I face when I think of doing a POTA activation is what to bring and how best to organize my gear so I have what I need. The easiest thing to do is consider what you MUST have in your POTA equipment cache. Secondly, list the necessities to get your station on the air in the field. If you forget to bring the manual for your transceiver, some coax adapters, or various lengths of complete jumper coaxial cables, it might make the difference in whether or not you get on the air. I have two ‘bags’ plus my accessory bag containing everything I need to get up and running.

The first ‘bag’ is a hard case for my HF rig, VHF/UHF HT, power source, microphone, keyer, and antenna analyzer. Also included in this case are the operating manuals for the HF rig, the VHF/UHF HT, the power source, and the antenna analyzer.

The second ‘bag’ contains my antenna and coax. Within the confines of this small bag is my “Super Antenna” vertical, the precut-tuned radials from 80m through 10m. A mounting tripod, a ground spike antenna mount, a locking plier with a 3/8” to SO-239 connector welded to it, an HF frequency chart, and a 25’ length of RG-8X coaxial cable with PL-259 for the connection to the antenna end and a BNC connector on the other end for the input to my KX2 Rig. Plus, the tools to set the antenna up and set adjustments.

My accessory bag has various items I have sometimes seen needed on a portable radio setup. Although I am new to the POTA activations and hunting them, I have operated from many field locations in my 66 years as a ham radio operator.

MY GO-BOX CHECKLIST:

  • POTA Gear
    Elecraft KX2

    Elecraft KX2 w/KXPD2 keyer paddle & MH-3 Mic

  • Wouxon UV3D 2m/70cm HT & Whip Antennas
  • FlashFish 200W Solar Generator
  • Heil BM-17 earphones
  • Vibroflex Vibrokeyer CW paddle
  • AA-30 Antenna Analyzer
  • Solar-powered clock/thermometer
  • LED Light powered by Solar Generator
  • Frequency Reference Guide
  • Mini Log Book
  • FCC License
  • Elecraft KX2 Manual
  • FlashFish Solar Generator Manual
  • AA-30 Antenna Analyzer Manual 

MY ANTENNA GO-BAG LIST:

MP1C Super Antenna includes:

  • TM1 Low-Profile Tripod
  • UM2 Universal NVIS Super tilt Clamp Mount
  • SW1 Titanium Super whip

    POTA Gear
    MP1TRDX80 Superantenna
  • SP3 Super Spike Ground Mount
  • MC80 80-Meter Coil
  • MR Super Radial Sets = (40m-10m); (30m-17m); (80m-75m); (6m-4m-2m)
  • FG1 SWR Ruler
  • GB2 Super Go Bag
  • ER1 Extension rods
  • TW1 Telescopic Whip
  • PC1 HF Propagation Chart
  • Clamp and U-Bolt

Tools:

  • Hammer
  • Allen wrenches
  • Long-nose pliers/wire cutters
  • Adjustable crescent wrench

Extra Antenna items:

  • Locking pliers with 3/8”- SO-239 fitting
  • ~ 90’ of Extra flexible antenna wire
  • SIZE: The antenna extends to about 8ft tall. Collapsed Size: 12 inches. Go Bag Size: 13″x9″x3.5″ WEIGHT: The antenna weighs 1 pound. The antenna with accessories in the Go Bag is about 5 pounds. Maximum Power Rating: 500W SSB, 300W CW/DATA.
  • FREQUENCIES: ALL BANDS 80m, 75m, 40m, 30m, 20m, 17m, 15m, 12m, 11m, 10m meters (3.5MHz to 4.8MHz and 7MHz-30MHz) HF, plus VHF 6m (30MHz-54MHz) with a good SWR. Continuously tunes all frequencies: Marine, Government, NGO, CAP, MARS, EmComm, Shortwave, CB, etc. Direct Manual Tuning SuperSlider Coil, with Good SWR.
  • ANTENNA: The MP1C Antenna is at the heart of this high-performance system, with its high Q coil made of military-grade nickel beryllium resulting in repeatable precision.
  • TUNING: The FG1 Frequency Guide SWR Ruler calibrates a rigid polymer card in MHz and meter bands. With it, a good SWR is dialed in on all HF and VHF bands and then fine-tuned with my AA-30 Antenna Analyzer. There’s no need for an autotuner, but it can help extend the frequency range.
  • SUPERWHIP: The included SW1 ruggedized Titanium SuperWhip puts the Super Antenna in a ruggedized durability class beyond most regular ham antennas.
  • TRIPOD: The collapsible TM1 Low-Profile Tripod enables the antenna to be set up on any convenient flat surface, outdoors or indoors. 

ACCESSORY BAG CONTAINS:

  • 30-watt soldering iron w/solder
  • 3M waterproof Super 88 electrical tape
  • 3’ 50-Ohm BNC/BNC Coax Jumper Cable
  • 2’ 50-Ohm PL-259/PL-259 Coax Jumper Cable
  • AA Battery Pack for Wouxon UV3D HT
  • Assorted VHF/UHF, BNC, and SMA adaptors
  • AC/DC Power supply for KX2 and External Lithium-Ion

Fast Charger for the KX2’s KXBT2 battery

  • Wouxon UV3D battery charger
  • Bongo ties
  • LED flexible lamp
  • Multimeter
  • RCA to twin RCA splitter cable
  • USB to Micro cable
  • 5mm to 2.5mm 6’ audio cable
  • Programming cable for Wouxon UV3D
  • USB cable with AC to 5 VDC adapter
  • 2-Meter flexible J-Pole antenna w/BNC/PL-259/SMA adapters
  • Mini-bud earphones
  • External battery for cellphone – 9.6-watt hours – 5VDC in/5VDC out
  • Wall-wart power supply charger for Solar Generator 110/240 VAC in/15.0 VDC out
  • Transient voltage surge suppressor
  • MFJ Model 281 ClearTone external 8-ohm 4” speaker
  • 25-watt dummy load
  • Extra 2m/440 whip antennas

When building the case for the KX2 and the other items, I chose a hard-sided, oversized briefcase instead of a Pelican Box. I reasoned that I didn’t see the need for that order of protection with the way I operate on POTA activations. History may change my mind, but it has been more than adequate to serve my needs so far. I bought the case at Harbor Freight for $40.00. It came with pre-sliced foam for the bottom and an acoustic-like foam rubber top panel. The precut foam made it easy to make exact-size cuts to insert my Solar Generator and the KX2. The divider strips came with breakable stops to make it easy to make custom-divided sections in the case. I made a door-like cut in the top panel, and with Velcro, it now serves as a storage area for my manuals and paperwork. The total weight is around 15 pounds when loaded. Most of that weight is attributed to the 200W Solar Generator, about 4 pounds alone.

POTA GearThe internal KXBT2 Lithium-Ion battery pack In the KX2 provides 11 VDC @ 2.6 Ah, giving you about 8 hours of operation. It slowly recedes in power as the voltage decreases. The Solar generator plugs into the DC input of the KX2. When the power is less from the Lithium-Ion battery than the Solar Generator output, the KX2 automatically switches to the more prominent voltage source. I have a 100-watt foldable solar panel that inputs to the Solar Generator. However, you can’t charge its battery while it is running. Multiple Charging Outputs on the Generator Provide More Options: Features with AC/ DC/ USB OUTPUTS: 110 VAC output (200W), 2 DC outputs, 2 QC 3.0 quick charge USB ports, and 1 USB port (2.4A auto). It provides 151Wh (40800mAh) to power your transceiver, smartphone, tablet, laptop, camera, light, drones, fans, in-car appliances, CPAP machine, and more anytime. Triple Rechargeable Modes = Efficient Solar Generator: FlashFish power station’s Lithium-Ion battery pack can be charged by a 15-24-volt solar panel (not included), AC wall adapter, and car charger efficiently. There is no memory effect and no worry about battery capacity reduction.

Other items worth bringing along for your activation should include a lightweight, foldable table and a comfortable folding chair. A pop-up canopy is also a good idea if the weather is too sunny or the weather turns to rain. With all this gear, you might want to invest in a foldable wagon to haul it to your chosen spot after leaving your car. They typically cost about $70, but you will also find many uses around your home for them caring for household chores and at hamfests carrying about your newfound ‘treasures.’

A solar-powered 24-hour clock set to UTC gives me the exact time and the corresponding UTC date whenever I log my QSOs in a paper log book.

I now bring a wireless ‘Hot Spot’ from my cellphone carrier on these POTA activations. I can run my logging program on my tablet and use the wireless keyboard. I can still be online because I’ll have an Internet source at a reasonably remote location in the ‘Great North Woods’ of New Hampshire, Vermont, or Maine.

Although not required, legally, having a photocopy of your FCC license handy or mounted somewhere on your Go-Box is a good idea. If law enforcement, park rangers, etc., question what you are doing, it usually alleviates their concern about your presence and actions once a Federally-issued license is recognized. If you are entering a State or Federally-owned National Park, it is always a good idea to ask the person at the entrance about your antenna and whether they have any rules about using the trees as a support source.

Always try your gear at home or a nearby field location before heading out on your outdoor radio adventure. Set it up approximately the same as you will at the POTA event. You will be better prepared after doing so and could benefit from any faux pas you encounter during this practice session.

73 es GL de Jack WMØG

Activities, Featured, General

October POTA Activation October 15th – Mount Kearsarge

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October’s POTA activation will bring us back to Winslow State Park on the flanks of Mount Kearsarge. This park has a huge picnic area that we have used in the past . I’ve personally talked to the ranger in charge so she knows us and she loves hams!  The plan is to meet at the Winslow trail parking area this is at the end of Winslow House road also known as Kearsarge Mountain rd In Warner at 11 am on October 15th .  Here is a link to a map detailing the area. In addition the route is well signed from the highway to destination  so it’s an easy to follow drive.

You’ll also want to go to the NH State parks website to get a parking pass. Here is a link to The NH State Parks page where you can get that pass. In addition you’ll want to bring a fleece jacket and rain jacket, bug spray, sun block and a picnic lunch if you’d like. Also bring your  HT if you have one.We’ll be at a higher altitude so you might like to get a few VHF/UHF contacts as well.

Mount Kearsarge POTA
typical POTA setup

This is a POTA mentoring event so we will have multiple stations and antennas setup on different bands with a POTA coach at each one quite similar to a field day setup. If this is your introduction to POTA (Parks on The Air) fear not we can answer your questions and help you get on the air. All that’s needed is a willingness to learn. You don’t even need a ham radio license the coaches can be the control operator so bring an unlicensed friend!

If you have a mobile rig we will be listening to the N1IMO network of repeaters and  146.52 as well for chatting on our way up. If you have a GPS the physical address is 475 Kearsarge Mountain Rd. Wilmot, NH 03287. Make sure your GPS doesn’t try to default to another town. There are multiple towns in the area with Kearsarge Mountain in the name . If you have any questions email me and I can send more detailed instructions. It would be a good idea to email me anyway so we can get an idea of how many people to expect. My email is [email protected].

Hope to see you at the Mount Kearsarge POTA!

73′

Jim K1BRM

Antennas, Featured

What’s Inside the Hy-Gain AV-640 Vertical Matching Unit Anyway?

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With the exception of a 2m handheld and a temporary end-fed half-wave vertical[1] for use on 20m in the IARU CW contest, I have been off the air since July 2020. After assessing the rocky soil in the backyard, I have come to the conclusion that ground radials won’t be gobbled up by the lawn as they were by the St. Augustine Grass in Florida[2]. That’s when I decided to install a compromise antenna – one that does not require radials. Since I am apt to hang half-wave antennas for the top bands, I settled on the Hy-Gain AV-640[3].

The AV-640 is an 8-band antenna that, in addition to the WARC bands, adds 6m. Since I have not operated on the “magic band” for many years, it’s a nice bonus.

The AV-640 arrived from the supplier in a box that was intact, but the first thing on the to-do list was to complete a parts inventory. That task was completed in, maybe, two hours. During that time, the parts, particularly small hardware, were separated into several Ziploc bags for easy identification later.

It turned out that there were a few pieces of stainless hardware and mounting brackets missing, and MFJ, with help from DX Engineering[4], replaced them in record time. Encouraged by the quick replacements, I decided to perform one last check before installing the antenna. Like any good homebrew tinkerer, I decided to open the Matching Network, Figure 1, to see what was inside and to make certain that nothing was broken. My curiosity was rewarded. I found that two wires had broken, thereby, separating them from the printed circuit board. There was also a Ty-Rap normally looped through the circuit board to anchor the toroid cores that had snapped. MFJ gave me the choice of repairing the unit myself which would have required complete disassembly, or a replacement assembly. I chose the latter.

Figure 1. Interior View of the Hy-Gain AV-640 Matching Unit. Please click on the image to enlarge it. A 1:1 current UNUN (right) for common mode rejection is followed by a 9T:20T autotransformer (left) for a turns ratio of 1:2.22. The black and white wires are connected in series. The black wire is the so-called “common winding”, while the white wire is the so-called “series winding”. The circuit board traces can be seen from the top. The matching unit arrived damaged with a black and a white wire detached from the PCB. The points of damage are circled in white. The broken black wire should be soldered to the PCB within the toroid. A Ty-Rap had also snapped. The 1:1 current UNUN is visible to the right.

Under “Theory of Operation” the AV-640 manual describes[5] the matching unit as a “broadband RF transformer” in one sentence and later on as a “4:1 toroidal transformer (voltage balun)”. Since the copper on the backside of the PCB is visible from the top, the wiring could be traced without removing the circuit card from the housing. What I saw was something that was a 1:1 stacked-core current UNUN[6] for common mode rejection followed by a stacked-core autotransformer having a 9:20 turns ratio (in Figure 1, the broken black wire should loop through the toroid and be soldered to the PCB within the core I.D.)

The schematic of the matching unit is shown in Figure 2. The autotransformer has a 9-turn (common) primary and a 11-turn (series) secondary. The black primary (common) winding of 9-turns is in series with the white 11-turn (series) secondary winding to form a 9:20 turn autotransformer. The voltage turns ratio is 1:2.22, whereas, the impedance transformation ratio goes as N2, or 1:4.93. So, the autotransformer transforms 50 ohms to 247 ohms. A shortened radial ground plane, lowers the impedance at the antenna base.

Figure 2. Hy-Gain AV-640 Matching Unit Schematic Diagram. Please click on the figure to enlarge it. A 1:1 current UNUN is followed by an autotransformer. Note that the left end of the UNUN is dotted. The coax shield is wound with the same sense as the center conductor to form a common mode choke. An autotransformer that follows transforms the impedance from 50 ohms to 247-ohms. Note that the left end of the autotransformer is dotted. The black and white windings are wound with the same sense. Point D is connected to point A to place the primary (common) winding in series with the secondary (series) winding. The antenna is placed at DC ground potential by an RF choke that serves to bleed static charge from the antenna. The autotransformer is AC-coupled to the antenna by a high voltage ceramic capacitor. The short (72″ long) ground plane radials, depicted, lower the impedance at the antenna feed point to one that is more easily accommodated by the autotransformer. Please note that the ground return for the autotransformer and ground plane radial combination is brought back to the input connector via the common mode choke coax shield that is wound around the ferrite core. The 247-ohm impedance match at the antenna feed point is a compromise match for the 8 bands. As a practical consideration, a remote antenna tuner should be located as close to the matching unit as is practical to remove standing waves from the transmission line.

We might also take a look at the voltages at the secondary of the autotransformer to see if they are reasonable. At 100W we expect to see 70.7 Vrms (100 Vpeak) under matched conditions at the current UNUN input. If we multiply this by the 1:2.22 voltage turns ratio, we have 157 Vrms (222 Vpeak) at the antenna terminal. These numbers increase somewhat for 1.5 kW to 274 Vrms (387 Vpeak) and 608 Vrms (860 Vpeak), respectively.

It has been shown previously[7] that these numbers may degrade by as much as the square root of the VSWR. Thus, for a VSWR of 3:1, we might expect these numbers to increase by a factor of 1.732, and so on.

The lossy ferrite used in the UNUN and in the autotransformer places limits on the continuous (key-down) operation of this antenna. This subject was discussed in other posts[8][9].

For these reasons, this antenna has been rated for operation on each band within their 2:1 VSWR bandwidths[10].

References

[1] Blustine, Martin, Temporary 20m EFHW Vertical Installation, N1FD post, July 2, 2023. https://www.n1fd.org/2023/07/02/20m-efhw-vertical/

[2] Blustine, Martin, A Flagpole Antenna Project for Residential Settings, N1FD post, May 23, 2022. https://www.n1fd.org/2022/05/23/flagpole-antenna/

[3] Hy-Gain AV-640, HF VERTICAL, 8 BANDS-40/30/20/17/15/12/10/6 M, MFJ Enterprises, Inc., 308 Industrial Park Rd, Starkville, MS 39759. https://mfjenterprises.com/products/av-640

[4] DX Engineering, 1200 Southeast Ave.Tallmadge, Ohio 44278. https://www.dxengineering.com/parts/hgn-av-640

[5] Hy-Gain AV-640 8-Band Vertical Antenna, Instruction & Assembly Manual, Revised 14 July 2023, pp. 3-4. Hy-Gain, 308 Industrial Park Road, Starkville, Mississippi 39759. https://static.dxengineering.com/global/images/instructions/hgn-av-640_co.pdf?_gl=1*em8g2o*_ga*Nzc2NjgwNDEyLjE2OTQxMTU0MjQ.*_ga_NZB590FMHY*MTY5NDExNTQyNC4xLjEuMTY5NDExNTg0MS41MC4wLjA.

[6] Blustine, Martin, Differential and Common Modes on Transmission Lines – Part II, N1FD post, September 14, 2022. https://www.n1fd.org/2022/09/14/differential-and-common-modes-on-transmission-lines-part-ii/

[7] Blustine, Martin, Worst Case Standing Wave Voltage on a Transmission Line, N1FD post, August 1, 2022. https://www.n1fd.org/2022/08/01/standing-wave-voltage/

[8] Blustine, Martin, Power Losses and Dissipation in Various Ferrite Devices – Part I, N1FD post, August 10, 2022. https://www.n1fd.org/2022/08/10/ferrite-device-losses/

[9] Blustine, Martin, Power Losses and Dissipation in Various Ferrite Devices – Part II, N1FD post, August 12, 2022. https://www.n1fd.org/2022/08/12/ferrite-loss-2/

[10] Hy-Gain AV-640 8-Band Vertical Antenna, Instruction & Assembly Manual, Op. Cit., p. 5. https://static.dxengineering.com/global/images/instructions/hgn-av-640_co.pdf?_gl=1*em8g2o*_ga*Nzc2NjgwNDEyLjE2OTQxMTU0MjQ.*_ga_NZB590FMHY*MTY5NDExNTQyNC4xLjEuMTY5NDExNTg0MS41MC4wLjA.

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